i have just done this similarly and then found this thread.
i left the floss on my power head wich probley has bacteria and used up all my hydrogen peroxide.
i turned off canister filter
left on lights and co2
am also dosing excel regularly
mls measured using a flourish cap
i used 25 ml in a 40 b so i probley have about 35 gallons after plants substrate and plants so 25 ml of peroxide in 35 gallons
i have clado alge every where
will see if this works if not i will remove the floss next time